Without limiting the scope of the invention, its background is described in connection with a method for reducing boron diffusion through a gate oxide layer.
Integrated circuits using MOS transistors are used in many modern devices, including not only radios, TV, and stereos but less obvious items such as automobiles and microwaves. Integrated circuits are manufactured by processes involving hundreds of steps and these processes continue to evolve.
Recently, it has been determined that silicon nitride spacers are desirable in MOS transistor design since silicon nitride can be anisotropically etched with selectivity to the underlying oxide so that the silicon surface is not exposed to the etchants and excessive removal of oxide is minimized. Additionally, this nitride is not etched by subsequent oxide clean-ups and will serve as an etch barrier minimizing, e.g. source/drain shorting to the gate.